Safety-switch.



A. K. SUTHERLAND.

SAFETY SWITCH.

APPLICATION HLED JULY 31. 19 15.

1 ,229, 1 86. I Patented June 5, 1917.

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A. K. SUTHERLAND.

SAFETY SWITCH.

APPLICATION FILED JULY 31,1915.

1 ,229, 1 86. Patented June 5, 1917.

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A. K. SUTHERLAND'.

SAFETY SWITCH. APPLICATION HLED JULY 31.1915.

Patented June 5, .1917.

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UNITED STATES PATENT OFFICE.

ALEXANDER K. SUTI-IERLAND, OF NEW BRITAIN, CONNECTICUT, ASSIGNOR TO THE TRUMBULL ELECTRIC MANUFACTURING COMPANY, OF PLAINVILLE, CONNECTICUT,

A CORPORATION OF CONNECTICUT.

SAFETY-SWITCH.

Application filed July 31, 1915.

T 0 all whom it may concern:

Be it known that I, ALEXANDER K. SUTI-IER- LAND, a subject of King George V of England, and a resident of New Britain, in the county of Hartford and State of Connecticut, have invented certain new and useful Improvements in Safety-Switches, of which the following is a full, clear, and exact description, whereby any one skilled in the art may make and use the same.

The invention relates to switches and more particularly to what is termed herein a safety switch. It embodies not only a switch mechanism and means for actuating the switch, but also contemplates an inclosure for the switch which is directly cooperative therewith. The switch mechanism must be actuated in a certain and predetermined relation to the condition of the closure and furthermore, the switch mechanism must'be operated in a definite sequence of movements so that the circuits which it controls will be made effective in a certain pre scribed manner best adapted for the uses to r which the circuits are to be employed.

The switch parts in themselves are of the ordinary knife switch type.

The operating mechanism for-this knife switch type is peculiar in that it requires and necessitates a certain manipulation in certain sequence to eifect results; overcome objections and insure an operation which will be absolutely safe for the operator and absolutely safe for the translating devices which are to be actuated by the circuits controlled thereby.

It has been common practice to employ a knife switch having a double throw which in one position will effect certain results andin a second position will accomplish certain other results. Such devices have not. been free of liability of improper action and it is one of the primal intentions of the present invention to insure proper action and to safe-guard said action, as well as the operator. This is accomplished in part, by the inclosure for the switch mechanism which is so arranged that it is impossible for the operator to come in contact with the blades or parts of the switch while they are actively alive and in circuit.

The device illustrated and shown herein is primarily and particularly adapted for use Specification of Letters Patent.

Patented June 5, 1917.

Serial No. 43,035.

in connection with alternating current motors. It is to be employed as a starting switch.

It is a well known fact that an A C or induction motor requires an initial starting current of substantially three times that of the normal running load current. If the switch mechanism is fused to carry the running load only, the fuses are subject to liability of blowout when the initial starting current is used.

Provided the devices are fused to carry the starting current for the motor, they become absolutely -useless as a safeguard when the motor is running under low and normal conditions. The present device therefore contemplates a compulsory manual control for starting the motor under unfused con ditions.

\Vhen the motor is up to its proper cycle of operation and normal speed conditions, the switch must then by compulsion be thrown over into the running position. When so thrown over, it eifects the necessary contacts through a fused circuit, that is, a properly protected one for the normal running of the motor.

In addition to the compulsory conditions imposed upon securing a starting connection and a normal running connection, the device embodies certain interlocks in conjunction with the inclosing casing which absolutely preclude the possibility of improper operation. The interlocks are such that the inclosing casing must be secured in place, completely protecting all operating parts of the switch before it is possible to operate said switch either for starting or running connections.

The casing must remain closed, protecting the operator during either of the variations of the switch necessary to start or run a motor.

The sequence of operation of the switch is positively interlocked to prevent a false movement of the switch parts, thus necessitating an initial positioning of the switch parts for starting under the most advantageous conditions and running under the most normal conditions.

In fact, the operating handle and mecha nism for the switch while within ready ac cess, must be moved and actuated directly in accordance with the prescribed instructions for operation. Otherwise, the motor device or other device controlled by the switch cannot be actuated.

The objects of the invention are to provide a switch and controlling devices and mechanism therefor which will insure a definite sequence of operation for securing the various circuit connections.

A further object is to provide as a part of the operating mechanism, a complete ;inclo sure, the opening and closing of which will determine the possibility of operating the switch mechanism.

A still further object is to provide an interlock for the switch actuating devices and inclosing casing which will necessitate certain prescribed operations in order to make the circuit connections.

A further object is to necessitate direct operation by the operative during the continuance of the starting circuits and to immediately give an off or neutral position to the switch parts, in the event of failure on the part of the operative to complete the movements of the switch to that of a normal running position.

A further object is to provide interlocks which will necessitate throwing the switch to neutral position before access can be had to the mechanism through the cooperating inclosing casing.

Further objects reside in the simple form of construction and its details which make it possible to accomplish all of the above objects and results in a simple, expedient manner.

Referring to the drawings:

Figure 1 is a front face view of the switch mechanism and its inclosing casing, the door thereof being broken away and the parts being shown in section.

Fig. 2 is a side view of the switch and its casing.

Fig. 3 is a vertical section through the casing, illustrating the switch blades and appurtenant parts in side elevation.

Fig. 4 is a detail view of the interlock between the switch blade mechanism and the closure for the casing, the switch parts being in release position.

Fig. 5 is a similar view illustrating the switch parts locked and the door or closure partially open.

Fig. 6 is a detail view of an interlocking mechanism between the switch parts and door illustrating a modification in which said door is locked when. either the starting or running circuits are in operation.

Fig. 7 is a fragmentary perspective view of the switch handle and controlling gate therefor.

Fig. 8 is a fragmentary'detail illustrating a modified form of interlock between the door and switch mechanism.

Fig. 9 is a fragmentary detail of the hub of the switch handle and appurtenant parts.

Fig. 10 is a face view looking from the right of Fig. 9.

Fig. 11 is a plan'view of the gate or interlock for the switch handle.

Fig. 12 is a similar view illustrating the handle in forward position about to place the switch in initial running position.

Fig. 13 is a similar view with the switch handle moved into a farther position.

Fig. 14 is a diagrammatic view illustrating the wiring connections.

Hereinabove the various objects, purposes and intents of the invention have been set forth. It may be well to further indicate that the device contemplates a form requir ing safety first.

Outside of the advantages attained in pro viding a definite and positive sequence of movements for the switch parts which control the circuits, it is all important that there shall be no tampering with and no liability of damage to the operator from possible curiosity or desire to tamper with the switch devices.

lhe device as hereinafter more fully described precludes the possibility of attempting to fuse, investigate, change connections or in any way modify the initial installation without first having the switch in an oil circuit position.

It is absolutely impossible to open the door of the inclosing casing under any con ditions unless the switch is in off position.

It is equally impossible to manipulate the switch or move it from its off position until the door is closed.

These features are important in conjunction with the operation of a switch intended for use upon the circuits of given character and controlling devices of known requirements.

In the accompanying drawings, the numeral 1 denotes a casing which, as illustrated, is stamped up from sheet metal and is provided with a door 2, suitably hinged thereto. WVithin the casing, there is arranged an insulating switch base 3, which is preferably a slate slab or any suitable form of device which may be insulated from the casing 1 and will provide an insulating base for the various switch parts. Insulated openings are formed through the casing and are provided with suitable bushings for the inlet and outlet wires as at 4, 5, the preferred arrangement being to arrange a series of openings at the upper and lower sides of the casing.

The device, as illustrated, shows a threewire controlling switch having central supports 6 to which the oscillatory switch blades 7, 8 are pivoted as at 9. The incoming line wires are connected to the central supports w Au 6 in any convenient manner by suitable binding screws and the uppermost blades 7 are of the knife-switch type arranged to engage corresponding clips 10, which, through suitable fuses 11, are electrically connected with the terminals 12.

The switch blades 8 are also of the knifeswitch type and as illustrated, are integral with the blades 7. These cooperate with contact clips 13 which through the back of the insulating base 3 are electrically connected with the terminals 12.

The arrangement is such that when the switch blades 8 are in contact with their respective clips 13 an electrical connect on is made from the incoming line wires which are attached to the support 6 directly to the outlet terminals 12. It is obvious that in this position, the current is shunted past the fuses 11. I

lVhen the switch parts are in such position that the blades 7 are in contact with the clips 10, the circuit is closed from the incoming line wires through the supports 6 and passes through the fuses 11 to the terminals 12 and thence on to the motor or other translating device.

It will be apparent from the above that in one position of the switch blades 7 and 8, the current is passed directly to the terminals 12 and on to the translating device without passing through the fuses 11, while in a second position of the switch parts, the cur rent is passed directly through the fuses 11.

The purpose and intent of this arrangement is to provide for a starting current for motors which will be direct from the line to the motor as is the case when the blades 8 engage the clips 13. Under this initial starting current there would normally be liability of blowing the fuses which are intended to protect the translating devices under normal running conditions. As the switch parts are thrown to engage the blades 7, with the clips 10, the initial starting circuits through the blades 8 and clips 13, to the terminals 12 are broken and circuits are established directly through the clips 10, fuses 11, to the terminals 12 and thence to the motor so that in this position, the translating devices are subject to the protection of the fuses.

In order to provide for predetermined movements of the switch parts, a switch lever let is provided exteriorly to the case and this lever is secured to a short shaft 1 1" in any suitable manner as by the squared end 15 on a reduced portion 16 of the short shaft or stud 14 through the medium of a binding nut 17.

The shaft 14F extends through a tubular nipple 18 which forms a spring barrel for the spring 19 and is'provided with an eX- tended flange 20 by which it is secured to the side of the metallic casing 1.

The shaft 1 1 extends within the casing and has suitably secured to its inner end, as by a nut 21, an actuating arm 22. This arm extends along and parallel with a central insulating bar 23 of the switch blades 7 and 8. It is loosely secured thereto through suitable studs 24 having bushings 25.

The purpose of this is to permit a slight warpage or movement between the actuating bar 22 and the switch bar 23, otherwise it would be a mechanical necessity to actually center the shaft 14: with the center of movement of the switch blades 7, 8. The liability of binding and cramping under such conditions is immediately apparent and therefore the loose stud connections are effectual between the actuator bar 22 and switch blade bar 23. It is to be understood, of course, that the switch blades 7 and 8 with the bar23 are positively moved by the actuator bar 22.

The spring 19 which encircles the combined bearing nipple and spring barrel 18 is secured at one end in an opening 26 of the flange 20 and at its opposite end is hooked about the actuating lever 14. as at 27. This spring normally tends to hold the lever 14 in its central position, abutting against a stop 28 formed on the controlling gate 29. I This controlling gate 29 is secured to the outer face of the side of the inclosing casing 1 and has a radial top-part 30, conforming with the radius of movement of the lever and has stamped out from its central portion a stop lug 28.

At its forward end it is curved outwardly as at 31. Upon the lever 14, there is mounted a spring follower or latch member 32 which normally bears against the outside of the gate-plate 29 and abuts against the stop 28.

This arrangement of parts prevents moving the lever 1 1 from its normal position where its member 30 engages the stop 28 to the rearward position marked run on Fig. 2. This position would correspond to the normal running position of the switch with the blade 7 in engagement with the clips 10 directing the current from the line wires through the fuses 11 to the terminals 12 and the translating devices.

From the above it is apparent that the only movement which the lever 14: may have is toward the position start of Fig. 2 in which position, the line circuit is connected through the blades 8 and terminals 13 and intermediate connections directly with the terminals 12. This movement must always be against the tension of the spring 19 which normally tends tothrow the switch parts into the running position with the blade 7 in engagement with the clips 10. The stop 28 prevents such an engagement until after the lever 14 has been moved to its full forward position with the blades 8 in engagement with the clip 13.

A forward movement of the lever 14: is prevented by a locking member 33 which, through a spring 3 1, is normally held in looking position engaging a locking recess 22, of the actuator bar 22 and is only released from this locking position when the door or other closure 2 is completely closed.

The locking lever 33- is suitably pivoted as at 35 and always looks the switch parts against forward movement until the door is closed, thereupon, said lever is swung by the engagement of its end 36 with the inner face of the door and it is moved against the tension of the spring 34L until it releases the locking bar.

The locking lever 33 has a double function in that it serves as a spring opener for the door when it is unlocked. It is therefore apparent that the door must not only be closed but locked before the switch parts can be operated.

Arranged upon the inner side of the door 2 is a clip 37 and upon the actuating bar 22, there is a latch 38, as illustrated in Figs. 1 and 3.

As the switch parts are thrown into running position with the blades 7 in contact with the clips 10, the latch 38 engages the clip 37 and holds the door with an interior lock. It is therefore impossible to open the door until the switch is in the open or new tral position.

In Fig. 6 this arrangement is slightly modified by extending a latch piece 39 on both sides of the actuator bar 22 so that the door will be securely locked from the inside when the switch is in the initial starting position as well as when the switch is in the normal running position. This merely serves as an extra safeguard.

In either event, it is apparent that the operator can only open the door of the clevice and gain access thereto when the switch is in the off position.

He must, to operate the switch, first move it into the starting position and he must have the door closed and latched.

He must, owing to the tension of the spring, temporarily hold the switch in the starting position and immediately he releases his hold upon the switch, the spring 19 will carry the switch parts into the running position. During this movement under the spring tension, the spring stop member 32 will ride behind the gate-plate 29, passing over its outwardly curved end 31 and when it has reached the end of the segment 30, it will snap forward toward the switch handle so that as the switch is subsequently moved from the running position to the off position, said switch handle will be placed under the tension of the spring 19 and will en-- gage and will be locked by the stop 28 in its neutral position.

Only when it is in its neutral position is it possible to open the door of the inclosing casing.

On the exterior of the casing are stops 4C0, ll, the former limiting the movement of the switch handle and switch parts and securing proper registration for the starting position of the switch and the latter insuring positioning and registration for the normal running position of the switch.

In Fig. 8 there is illustrated a slightly modified form of interlock between the switch blade actuator 22 and the door of the casing.

It will be noted in this form that the parts are entirely within the casing and cannot be tampered with to release the switch even when the door is open.

In this figure, a pivoted lever 50 normally pressed under the switch blade actuator 22 by a spring 51 has an extended end 52 which will be engaged by a stud 53 when said stud is passed through a perforation 54: in the front jamb of the .inclosing casing. Obviously, this necessitates complete closure of the door before the switch parts are released so that said switch may be manipulated by the handle l t for the starting of the motor.

It is apparent from the above description, that a definite sequence of operation is important. First of all, the casing must be closed in order to manipulate the switch and secondly, the switch must be manually held there under tension of the spring 19. m

lhirdly, a release of the switch handle after being brought forward into starting position, will immediately carry it into the running position. Fourth, it will remain in the running position until manually moved into the neutral position and there it will be locked against re-insertion for the running position until it has first been moved forward into the starting position.

During the positioning of the switch either for starting or normal running, the casing will be locked from the inside by the manipulation of the switch parts. It is therefore apparent that the switch must always be in neutral position in order to open the door for the purposes of re-fusing or such other purposes as may be desired.

lVhat I claim as my invention and desire to secure by Letters Patent is:

1. A safety switch consisting of a switch mechanism having switch contacting members for controlling a plurality of circuits, a housing inclosing said switch mechanism having a door, a switch actuator and means for locking said switch actuator against movement except in a predetermined cycle of operations and cooperative means between the door of the housing and switch mechanism for preventing operation of the controlling a plurality of circuits, one of switch actuator except when said housing and its door completely incloses and protects the switch mechanism.

2. A safety switch consisting of a switch mechanism comprising a plurality of circuit controlling terminals and a switch for opening and closing the connections for said terminals to complete or break a plurality of circuits, a single actuating device for mov ing the circuit controlling devices of the switch, a housing for said switch including a door therefor and means intermediate said door and housing and switch actuator for controlling the operation of the switch parts by the actuator.

3. In a device of the character described, a housing, terminals arranged therein, a switch mechanism and electrical connections controlled thereby with reference to the terminals, an actuator for the switch exteriorly arranged to the housing and normally locked against movement in one direction, locking and releasing devices intermediate the housing and switch parts for controlling the operation of the switch and interlocking devices appurtenant to the switch actuator for determining the cycle of operation thereof and of the switch and all controlled by the locking and releasing de vices of the housing and its door.

4. In a device of the character described, a knife switch having a plurality of blades controlling a plurality of circuits, an actuator for moving said blades into and out of engagement with cooperating contact clips,

contact clips forming terminals for the re spectlve knlfe switches, a res1l1ent connec- 131011 for the actuator for normally throwing one set of blades of the switch into one posi- U011, said res1l1ent means compelhng manual holding of the actuator and one set of the switch blades in position for controlling one of the circuits and a controlling gate and interlocking devices for determining the sequence of movement of the actuator A before and after it has been manually moved and held to close one of the circuits.

5. A safety switch having an mclosing casing and a door therefor, a swltch device said circuits connected directly with a translating device, the other of said circuits connected therewith through fuse devices, manually actuated means for throwing said switch and compelling the holding thereof to close the direct connections to the translating device including resilient means for compelling manual retention of the switch parts in closed position for the direct connection, said resilient means adapted upon release to throw the switch parts into the fused circuit connections and interlocking devices compelling and defining a definite cycle of operation for the switch devices under both manual and automatic actions.

6.. In a device of the character described, a casing, a switch mechanism arranged therein, an actuator mounted exteriorly upon the casing and controlling the position of the switch mechanism when released, a locking member adapted for locking and releasing actions with reference to the switch mechanism dependent upon the position of the door, a door for said casing, cooperating with a locking member actuated upon opening and closing of the door, and devices appurtenant to the exterior switch actuator compelling and defining a predetermined cycle of operation thereof with reference to the switch mechanism.

7. In a device of the character described, a casing, a knife switchmounted therein and comprising a series of pivoted blades united by a common cross-bar, terminal connections for each set of blades, an actuator bar loosely connected with the common crossbar of said blades, an actuating lever exteriorly mounted with reference to the casing and connected with the loosely connected actuator bar, a spring for normally holding said actuator and connected parts in predetermined position, a stop limiting the move ment thereof under spring tension, interlocking parts permitting a movement of the actuator in one direction only under tension of the spring and by manual operation, a lock for the actuator bar normally preventing movement thereof, means for releasing said lock and means for compelling'a predetermined cycle of operation of the actuator both under manual and automatic spring operations.

8.- In a device of the character described embodying a housing having a door and a switch mechanism arranged therein, an actuating lever arranged exteriorly to the housing and connected for moving and controlling the position of the switch mechanism of interlocking members upon the door and switch mechanism for interiorly looking said door in closed position during certain positioning of the switch mechanisms and an interlock between said door and switch mechanism preventing operation of the switch by its actuator except in predetermined manner and only when said door is in closed position.

9. In a device of the character described embodying a housing having a door and a switch mechanism arranged therein, an actuating lever arranged exteriorly to the housing for controlling and defining the po sition of the switch mechanism of interlocking members one upon the door and one upon the switch mechanism for interiorly locking said door in closed position during certain positioning of the switch mecha nisms and an interlock between said door and switch mechanism preventing operation of the switch through its actuator except when said door is in closed position, and a controlling gate for the actuator and a follower traversing said gate and mounted on the actuator whereby said actuator must be moved in a predetermined cycle of operation whether normally moved or moved by the spring-actuating means.

10. In a device of the character described a housing having a door, a switch mechanism arranged therein adapted to control a primary and secondary circuit, an interlock between said door and switch mechanism locking the latter against movement when the door is in open position, an actuator for the switch mechanism eXteriorly arranged upon the housing, a controlling gate for said. actuator having a stop for positioning the actuator with the switch mechanism in neutral position, a spring normally holding said actuator against the stop though permitting movementof the actuator with reference to the controlling gate and stop members for limiting the movement of the actuator under manual or automatic spring control.

ALEXANDER K. SUTHERLAND.

Witnesses:

AXEL H. BERGENDAHL, GEORGE A. CASE.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

